Exercise 6-5 (Algo) Changes in Variable Costs, Fixed Costs, Selling Price, and Volume [LO6-4] [The following information applies to the questions displayed below.] Data for Hermann Corporation are shown below: Fixed expenses are $72,000 per month and the company is selling 4,200 units per month. Exercise 6-5 (Algo) Part 1 Required: 1.a. How much will net operating income increase (decrease) per month if the monthly advertising budget increases by $9,600, the monthly sales volume increases by 100 units, and the total monthly sales increase by $6,000 ? 1-b. Should the advertising budget be increased